Large mammal population declines in Africa’s protected areas

Protected areas (PAs) are the cornerstone of global conservation efforts but their performance in maintaining populations of their key species remains poorly documented. Here, we address this gap using a new database of 583 population abundance time series for 69 species of large mammals in 78 African PAs. Population abundance time series were aggregated to form a multi-species index of overall change in population abundance. The index reveals on average a 59% decline in population abundance between 1970 and 2005. Indices for different parts of Africa demonstrate large regional differences, with southern African PAs typically maintaining their populations and western African PAs suffering the most severe declines. These results indicate that African PAs have generally failed to mitigate human-induced threats to African large mammal populations, but they also show some successes. Further development of our index could help to measure future progress towards post-2010 targets for reducing biodiversity loss.     

Exploring the effects of the vegetation on passive tracer transport by using the multifractal analysis

Multifractal turbulence formalism has been used to describe the time series in simulated passive tracer transport in a vegetated open-channel, phenomenon characterized by a high temporal non-linear variability. A study of the empirical statistical moments scaling function for several scale ratios reveals the presence of a multifractal phase transition associated with one critical moment. The parameters of the universal multifractal model have been estimated using the double trace moment method. The theoretical statistical moments scaling was simulated by using the universal multifractal model showing an acceptable agreement with the corresponding empirical function. The universal multifractal parameters estimated here have different values to those reported for obstacle-free phenomena such as the atmospheric turbulence and passive scalar transport in turbulent oceanic flows.     

白河流域水质时程演化特征分析

根据1991～2006年16年的水质监测数据,选取高锰酸盐、氨氮、溶解氧3项指数,运用单因子指数、综合指数评价方法对白河流域水质进行分析,通过水质的逐月变化及逐年变化比较,探索白河流域水质时程变化特征,同时结合秩相关系数法（Spearman）对水质趋势进行分析,最后提出保护建议措施：     

Temperature Relations of Germination in Acer platanoides L. Seeds

The aim of this study was to describe the effect of temperature on the germination response of Acer platanoides L. seeds and the possible influence of dormancy. Moist chilled seeds (fruits) from eight trees were germinated at eight constant temperatures from 3 to 32C for 30 days. The highest germination was obtained at temperatures below 10C and the highest rate of germination was between 22 and 28C. The critical lower temperature for germination was estimated to be -2.6C, and the critical upper temperature between 30 and 35C. Temperatures above 10-15C increasingly inhibited the germination of seeds. Some of the non-germinated seeds were able to germinate after a second chilling period, possibly as a consequence of further release of primary dormancy and an indicated secondary dormancy. Seed survival decreased with increasing temperatures above 15C. The rate of germination was correlated with the accumulated thermal time at suboptimal temperatures. In conclusion, a constant temperature of 10C is recommended for testing the germination of seeds of A . platanoides.     

“非临时性”景观设计方法探讨

以景观行业临时性景观频出的现象为出发点,结合案例,从时间,记忆、情感三个方面探讨非临时性景观的设计方法,深入挖掘非临时性景观建设的必要性及其核心价值,并针对性的提出了设计方法。     

昭通市苹果园昆虫群落时间格局与害虫防治

 1994年4月至9月在昭通市苹果园进行昆虫群落系统调查,根据调查结果,应用最优分割法,将昆虫群落的时间变化分为4月上旬至7月下旬,8月上旬和8月中旬至9月下旬3个有序阶段,揭示了各阶段害虫、天敌的发生特点,提出了防治意见。     

利用时域反射仪测定饱和砂土中非水相液体

利用时域反射技术,以饱和砂土和菜籽油、机油为研究对象,室内模拟研究了非水相液体(NAPLs,nonaqueous phase liquids)污染土壤的介电常数和电导率的变化规律,确定了饱和砂土中NAPLs含量的预测模型。研究表明:1饱和砂土中体积含油量在0~0.05 cm~3/cm~3时,土壤介电常数并无显著变化;随着NAPLs体积含量的进一步增加,介电常数呈线性减小趋势;土壤体积质量和NAPLs类型对相同饱和度的土壤介电常数未产生影响。2饱和土壤的电导率与NAPLs含量存在良好的线性负相关关系(R2=0.96);土壤体积质量对相同饱和度的土壤电导率未产生影响。3混合介电模型(a=0.5)高估了饱和砂土中NAPLs含量,平均RMSE为0.038 cm~3/cm~3;参数a调整为0.52后,混合介电模型提高了预测精度,比原混合介电模型(a=0.5)预测精度可以提高23.2%。本研究结果表明可利用时域反射技术监测污染土壤的介电常数与电导率并测定饱和土壤中NAPLs的含量。     

太行低山区荆条耗水特征及其与参考作物蒸散量的关系

荆条是太行低山区常见的典型灌木,因其具有抗逆性强、耐贫瘠等特点,在水土保持、生态修复、山区绿化等方面广泛应用。研究荆条耗水变化规律不仅可以揭示其耗水机制,还能为植被恢复重建与管理提供理论依据。本研究采用大型称重式蒸渗仪搭配自动气象站的方法,对太行低山区乡土灌木荆条的耗水及气象因子进行观测,同时利用FAO-56 Penman-Monteith公式结合相关气象因子计算参考作物蒸散量（ET0）,揭示不同时间尺度下荆条的耗水特征及其与ET0的关系。结果表明：（1）日内尺度上,荆条耗水表现为单峰曲线,与太阳辐射（Ra）、气温（Ta）及饱和水汽压亏缺（VPD）趋势一致,而与相对湿度（RH）相反,荆条耗水峰值出现时间略滞后于Ra。日尺度上,荆条耗水表现为“弱−强−弱”的趋势,即生长季前期与后期日耗水强度较小（分别为1.50mm和2.00mm）、中期较大（4.00mm）,生长季内最大和最小日耗水分别出现在8月29日和10月9日,大小分别为6.38mm和0.20mm。月尺度上,荆条耗水表现为8月>7月>9月>10月>6月>5月,主要生长季节荆条共消耗水分513.5mm,同期降水526.6mm,整体上降水可满足荆条耗水需求,但5−6月降水较少,荆条易遭受季节性干旱。（2）荆条具有较强的环境适应性与生态可塑性。在雨季,荆条生长旺盛,水分传输率高,耗水量大;在干旱季节,荆条启动自适应机制,减少水分消耗。（3）荆条日耗水与日ET0之间关系表现为：干旱季节（5−6月）二者相关性较差,降水充沛的季节（7−10月）二者表现为很好的对数关系（R2=0.7431）。利用建立的拟合方程对荆条耗水进行估算,并与实测值进行对比,发现估算值与实测值具有较好的一致性,误差小,说明在降水充沛的季节可利用拟合方程对荆条耗水进行估算。